I play quite often on a large hollow wooden stage and the Gramma pad was a huge improvement for getting less boomy mud. Sound was more articulate and cut through the mix better with the gramma pad. I wont play without it anywhere. It is now standard equip. for me.

Thanks for the great feedback. Such a simple, low cost fix to get a better sound. I will have to check one out soon. Does it also help if you are on a really solid stage, or tucked away into the corner...

I believe the Gramma Pad is "high-tech" form designed for acoustic isolation and to support the weight without collapsing (sorry for the poor spelling). You could be hit or miss on foam you identify, purchase and use to make your own support.

What is the difference between a Gramma pad and a piece of plywood covered with foam?

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Virtually nothing. The gramma looks nice. But I imagine one could make one with some automotive carpet and a piece of 1/2" plywood, glue/staple on some black eggshell foam or something, and you'd be set.

The Gramma's used to be $29.00 when they came out, and I grabbed one. But at the price they are now, I've taken a pass on them.

I used mine about 6 months, and honestly? I didn't notice a difference. But that doesn't mean they won't in your situation.

Maybe grab some foam and set it under your amp for a test. If it works, splurge on the real Gramma. If not, don't.

What is the difference between a Gramma pad and a piece of plywood covered with foam?

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Great thought Jimmy. I have wondered this myself... It looks like an idea worth exploring though. Cheaper than buying a new amp or bass or other extreme measures that we have ALL taken, in the pursuit for a clearer live tone.

Great thought Jimmy. I have wondered this myself... It looks like an idea worth exploring though. Cheaper than buying a new amp or bass or other extreme measures that we have ALL taken, in the pursuit for a clearer live tone.

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Yeah, but if it's snake oil, you just spent $50 on a piece of wood covered with foam. Not saying that it's snake oil since I've never seen it, but I fail to see where acoustic coupling can be removed simply by sticking your amp on a piece of wood covered with foam. Especially when Bill Fitzmaurice says you have to elevate your amp like 28 inches before you get rid of floor coupling.

I play on a lot of hollow wooden stages and just use two small strips of Auralex Platfoam under my rig and this really helps our on stage sound.
Its much better than the cab being on the floor as it helps control the low end but it doesn't loose all the low end like i find happens if i use a beer crate or chair.
I guess it could just be down to the cab being a few inches off the floor but it does make a difference.

I do intend to get a proper Gramma pad one day but for now im happy with just the foam.

Just to manage the OP's expectations, I use mine to keep the amp from rumbling on temporary (typically outdoor stages), but it's not going to keep your sound from bouncing all over the place in a school gymnasium ... once the sound is projected off the stage, you can't change the sound of the "room" ... gyms just have bad acoustics, Gramma or not, expensive bass amp or not.

And yes, I love mine (bought used, hard to justify the price when new), but in terms of the reason I bought it for ... again, playing on temporary stages and preventing the loud rumble caused by my amp vibrating through the stage floor.

I swear by mine. Use it at all live gigs. I've seen particular improvements using them on hollow stages as well as bars with concrete floors. The Gramma's use several different types of Auralex Soundproofing foam designed for studio use under the pads.